Most people tend to prefer 'warm white' light. In fact, we have been conditioned to find warm appearing lamps 'normal' at low lighting levels, since it mimics the colour of fire which we have used as a light source for thousands of years.

Cool White is generally the preferred colour for work areas and offices, while daylight is used in some shops and areas where a blue/white light is preferred.

Although different bulb suppliers describe the light colour in different ways, the colour temperature marked on the pack is the best guide to the colour of light you’ll receive. 'Warm white' is often used to describe 2700K or 3000K , 'cool white' equates to 4000K and daylight colours will be marked at around 6000K or higher.

Why is “colour temperature” important?

Colour temperature of light sources is measured in kelvin (symbol: K).

While this may not have been important to know when the only light bulbs available for your home were standard incandescent and they all came in one standard colour of “warm white” (or 2700K), new technologies now provide you a choice of colours. So it’s important to choose the right colour to get the look you want. Different colour temperatures are useful for different lighting purposes.

Choosing the right light colour isn’t difficult. It’s just a case of understanding the different colours available and matching the right bulb to the right application.

'Warm White' (2700K – 3000K)

This white gives off yellowish light that helps enrich the warm colours in your home, like wood. They are more suitable for lounges, hallways and bedrooms – areas where people relax. “Warm white” is the same colour temperature as the standard inefficient incandescent bulbs.

'Cool White' (4000K)

'Cool White' looks crisper under higher colour temperatures and appears more 'normal' in high lighting level situations. As a matter of fact, 'cool white' gives off a bluer light that improves our ability to see contrasts, making it ideal for work areas such as kitchens, laundries, workshops and offices (not to mention being great for reading lamps).

Daylight (6000K and above)

Daylight lamps appear to be cooler or ‘bluer’ than ‘normal’ lamps and are generally used for special applications only. These might be areas where high quality colour rendition is required where they may be mixed with a warm white lamp for this purpose, They may be used on their own such as in shop lighting when special effects are required or a ‘cool’ appearance is required in places of entertainment.

Choose the bulb type to match the white you want 

A standard incandescent bulb has a slightly yellowish 'warm' white light (2700K), while halogens are 'whiter' at about 3100K.

With both of these bulb types you 'get what you get' in terms of whiteness. But with LEDs and fluorescents (both linear fluorescent tube and CFL) you have a wide choice of colour temperatures to choose from.

The bulb colour should be clearly labelled on the packaging and it is makes it important to check this when choosing the best bulb for your needs (if you purchase a 6000K ‘daylight’ bulb in your lounge, it’s unlikely to remain a space to relax in).

The choices, from ‘warm’ to ‘cool’ are typically: 2700K (warmest), 3000K, 3500K, 4000K, 5000K, 6000K and 6500K and above (coolest).

Accurate colour rendering

Colour rendering is a measure of the ability of a light source to reproduce the colours of various objects faithfully in comparison with an ideal or natural light source. The general colour rendering index (Ra) rates colour rendering out of 100. The higher the index, the better the colour rendering and different light sources have different colour rendering characteristics.

New generation halogen bulbs and halogen spot lights (also known as tungsten halogen bulbs) and traditional incandescent bulbs produce light by having their filament heated. Because they produce all wavelengths of the spectrum, they have a colour rendering of Ra100 (which, in plain English, makes them the best lights you can use to see all colours accurately).